In the manufacture of lead acid, and similar, batteries it is known to have to assemble groups or stacks of battery plates for insertion in the compartments of the battery box. Frequently alternate plates are enveloped in porous separator material, although at times it is necessary that adjacent plates are both enveloped or there may be an unenveloped pair in the group. Apparatus is therefore provided for assembling appropriate groups and typically there is an upstream plate feeder, which feeds plates onto a central conveyor upstream of an enveloper, which envelopes the plates coming down that section of the conveyor. One or more further plate feeders are provided downstream of the enveloper so that desired sequences of enveloped and unenveloped plates travel down the conveyor. At the end of the main conveyor the plates pass into a pocketed conveyor, which is timed to receive the desired group or stack of plates within its respective pocket. The stacking conveyor has a buffer zone which passes under a group handling device, which removes the assembled groups out of the stacker and places them onto a feed for a cast-on strap machine, where the groups have their terminals cast-on, prior to insertion into the battery boxes.
This arrangement used to work perfectly well, but in more recent years the speed of the cast-on machines and the other parts of the line downstream from the group forming apparatus, has increased significantly and thus more rapid supply of formed groups has been required.
At first sight, a person not skilled in the art might have thought the solution was simply to buy two stacking lines to feed the cast-on machine, but this simply has the effect of doubling up the labour, quite apart from increasing the capital cost and the approach is not economically acceptable to the industry. Attempts have therefore been made to increase the speed of the existing apparatus, in particular by doubling up the plate feeds both upstream and downstream of the enveloper. Some high speeds, in terms of plates per minute, have been claimed for such arrangements, but in practice there are significant limitations when one comes to running the apparatus on a production basis. This is because at speeds above about 150 plates per minute the plates and enveloping material are travelling so fast that aerodynamic affects become progressively more significant making it much harder, if not impossible, to control the correct sequencing of the apparatus. Further at the point of transfer the plate is expected to come to rest before it is picked up by the fingers on the main conveyor. At these elevated speeds the plates have often not settled. The resultant mis-timings and mis-aliginments will frequently cause jamming of the machine and it will be appreciated that, at these very high speeds of operation, any blockage on the main conveyor, quickly creates a significant pile up of plates, even in the short time that it may take for such a jam to be detected.